Question

When my app closes will the values i have set still be there when I re open it?
Or is there a way to save them somewhere?

Answer 1

No they won’t,

When you jump-out from the application, application will go to a state called TombStoned, it is your responsibility to store and retrieve useful page elements.

In order to do this, you need to store information on the following event on your page:

public override void OnNavigatedFrom(...)
{
    State["XXX"] = txtName.Text; // save your data on page state (keep it low in size!)
}

the same way you need to retrieve your data on the following event

public override void OnNavigatedTo(...)
{
    txtName.Text = State["XXX"]; // read your data from page state
    // also check if state has any entry with this key
}

If you need to store application level data, you need to do it in your App.xaml.cs in the following events:

public override void OnDeactivated(...)
{
    // Store in IsolatedStorageSettings
}

public override void OnActivated(...)
{
    // Read from IsolatedStorageSettings
}

For more details about Tombstoning read the following article:

http://www.scottlogic.co.uk/blog/colin/2011/05/a-simple-windows-phone-7-mvvm-tombstoning-example/